Examples of such gas sensors are infrared optical gas sensors and catalytic heat tone sensors, which are also used as so-called explosion-proof gas sensors in stationary operation in order to determine combustible gases and the concentration thereof in the ambient air or atmosphere. Within their housings, these gas sensors have a measuring cell, in which the gases to be measured are detected on the basis of physical processes, such as infrared absorption or heat tone. The gas to be measured now enters the gas sensor through openings in the housing or in the measuring cell of the gas sensor, and the response time of the gas sensor to the particular gas to be measured depends on the number and the arrangement of these openings. The larger the number of openings in the housing or in the measuring cell, the more rapidly can the gas to be measured diffuse into the gas sensor. However, there is a risk in case of gas sensors for combustible measured gases such as methane that the gas being measured can be ignited within the measuring cell by heated and electrically operated sensor elements or measuring elements. To prevent the spark generated from spreading into the environment of the sensor, so-called flame traps must be located at the housing openings. These are embodied, in general, by individual sintered metal elements, as they appear, for example, from EP 0 182 064 A1, by which the gas being measured, which is ignited within the measuring cell in the gas sensor, is cooled so intensely during flowing out that the measured gas located outside the gas sensor cannot be ignited. The entire housing construction of the gas sensor must be such that the explosion or flashback protection is still guaranteed even after strong external mechanical effects. The gas sensor housing itself must be manufactured from a mechanically resistant material and, in particular, precautionary measures must be taken to prevent damage to the sintered elements. One possibility of embodiment is the protection by a stable component arranged on the outside, which is permanently attached above the sintered element. One drawback of this solution is the increased manufacturing cost for the gas sensor due to the additional component. On the other hand, the diffusion of the gas to be measured into the measuring cell is compromised by part of the surface of the sintered element being covered, as a result of which the gas sensor will have an undesired, long response time.
An alternative solution for protecting the sintered element is the structural integration in the housing, so that complete flashback protection of the housing is achieved and the sintered element itself cannot be damaged. However, this solution also involves the drawback that the diffusion of the gas to be measured into the measuring cell is more difficult, which is associated with a longer response time of the gas sensor, and that additional components and assembly steps become necessary.